Studies of titanocene and zirconocene pyridine-2,6-bis-thiocarboxylates exhibiting partial desulfurization

Attempts to synthesize bent metallocene complexes of pyridine-2,6-bis(thiocarboxylate), Cp2Ti(pdtc) and Cp2Zr(pdtc) yielded partially desulfurized products. In the case of Cp2Ti(IV) two types of products were obtained, in one case desulfurization was at one of the thiocarboxylate groups resulting in a carboxylate group while in the other case it was partial and from both the thiocarboxylate entities. In case of Cp2Zr(IV) similar partial desulfurization took place from both the thiocarboxylates. The complexes have been characterized by single crystal X-ray diffraction analysis. The ligands pyridine-2-carboxylate-6-thiocarboxylate, pyridine-2,6-dicarboxylate and pyridine-2,6-bis(thiocarboxylate) act as tridentate ligands. With both the metals binding of ligand is through the oxygen (and nitrogen) atoms leaving the sulfur free. Electronic absorption and emission spectra of the compounds have been studied experimentally and explained on the basis of DFT computations.